Cartridge fuse



Feb. 19, 1929. 1,702,353

C. T. M DONALD ET AL CARTRIDGE FUSE Filed. Nov. 11, 1925 Patented Feb. 19, 1929.

UNITED STATES PATENT OFFICE.

CLARENCE '1. MCDONALD AND HERBERT RAY COOK, OF CHICAGO, ILLINOIS, ASSIGNORS TO CHICAGO JEFFERSON FUSE 8: ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

CARTRIDGE FUSE.

Application filed November 11, 1925. Serial No. 68,253.

The invention relates more particularly to cartridge fuses of the knife blade type in which the fusible element is renewable, it being the general object of the invention to provide a new and improved fuse of this type of a simplified construction particularly adapted to save time and labor when renewing the fusible element.

Another object of the invention is to provide an improved cartridge fuse of the renewable type in which the majority of the elements which are removable from the casing are incorporated in a terminal blade unit in a manner such that when the fuse is disassembled for the purpose of renewing the fusible link there is a minimum number of separated parts.

Another object of the invention is to provide a terminal blade unit for a cartridge fuse, of an improved construction whereby the fusible element may be replaced quickly and easily by a simple manual operation and in which the terminal blades are secured in rigid alinement by means of an insulating bridge section also adapted to be replaced readily. I

A further object of the invention is to provide a cartridge fuse with novel means for securing the terminal blades in place in the casing and for closing the ends of the casing.

In pursuance of the foregoing objects, we

' aim to provide a renewable cartridge fuse comprising a casing of insulating material having a metallic head or bushing secured to each end thereof, and a terminal blade unit adapted to pass through said casing and be secured to said heads, said terminal unit consisting of a pair of contact blades joined by a fusible link and secured in spaced relation by an insulating bridge section, and means to clamp the bladesdetachably to the heads, said terminal blade unit being adapted to be withdrawn completely from the casing upon said clamping means being released.

Further objects and advantages will become apparent as the description proceeds.

In thedrawings Figure .1 is a longitudinal View partly in central section of one form of the inven tion.

Fig. 2- is a similar view taken in a plane at right angles to that of Fig. 1. i

Fig. 3 is an elevational view of the terminal blade unit.

Fig. 4 is a view similar to that in Fig. 3, of a modified form of the invention.

Fig. 5 is a section in the plane of line 55 of Fig. 2 with the end cap removed.

Fig. 6 is a section in the plane of line 66 of Fig. 2 with the end cap removed.

Fig. 7 is a view of one of the end washers.

While our invention is susceptible of embodiment in many different forms, we have shown in the drawings and will herein describe in detail two such embodiments with the understanding that the present disclosure is to be considered as an exemplification of the principle of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

In the exemplary forms illustrated herein, the invention embodies a casing comprising a cylindrical tube 1 of fibre or other suitable insulating material, and two metallic heads or bushings 2 secured to the opposite ends thereof in a suitable manner such, for example as by means of the screw threads 3 or the rivets 4, or both. These heads preferably at their outer ends have end walls or webs 5 forming alined non-circular aper tures 6 therein, these apertures being hereii shown as substantially rectangular in shape and identical in size. Two of the webs of each head are provided with opposed notches 7 offset from the central portion of the webs as shown in Figs. 5 and 6.

The terminal blade unit which carries the fusible element may be of various forms, the preferred forms illustrated in the drawings comprising pair of knife blade terminals 8 and 8, one or more fusible elements 9 connecting the terminals, a bridge section composed of metal blocks 10 and an insulating member 11 securing the blades together in spaced relation, two plates 12 and 12 fixed. respectively to the blades 8 and 8 and transversely thereof, a metal washer 13 and an end cap 14, the metal washer and the cap being retained permanently on the blade 8 by means of one or more projecting or upset portions 22 on the blade. The knife blades 8 and 8 are provided with shoulders 15 formed on the opposite edges thereof, the inner portions 16 of the blades being narrower than the outer or terminal portions. ihe plates 12 and 12 which have apertures therethrough to permit the entrance of the portions 16 of the blades, are secured against the shoulders 15 by any suitable means. These shoulders extendbeyond the edges of the plates and abut the outer side of the webs 5 of the heads 2 to prevent inward movement of the blade in the casing when positioned axially thereof, as shown for the left hand end of Fig. 1, the plates 12 and 12 then being positioned in the planes of or flush with the webs 5 and within the apertures 6. The plate 12 is of a size-to fit snugly in and to close the aperture of one head to hold the blade 8" central thereof and against rotary movement in the casing as shown in Fig. 6. The plate 12 fits snugly against three sides of the aperture 6 of the other head to partly close said aperture and to prevent rotary movement of the blade 8 in that head when the blade is central thereof, said plate being narrower on one side of the blade to permit lateral movement of the blade in the aperture to a position eccentric of the casing from which the terminal portion of the blade may pass between the notches 7 (see Fig. 5 wherein the position of the terminal portion of the blade is shown in dotted outline).

The metal blocks 10 are preferably rigid with the insulating member 11, being secured thereto by suitable means such as, for example, rivets 17, to thereby form a unitary bridge section. This bridge section and the fusible links 9 are herein shown'connected to the terminal blades by means of suitable fastening devices such as cap screws 19 and washers 20, the cap screws being adapted to pass through apertures in the links and blades and and into screwthreaded engagement with the blocks 10, the said blocks then being preferably in abutment with the plates 12 and 12 As these devices must necessarily be loosened and tightened, each time the link 9 is renewed, the blocks 10 are preferably of hard metal such as iron or steel to provide durable anchoring means therein. In this way the difficulty usually experienced with worn threads in copper blades, or with a loose bolt and nut, is eliminated.

In addition to the screws 19 means is preferably provided to cause interengagement of the blocks 10 and the knife blades at points spaced from the screws 19, such means being herein shown as comprising screws 18 passing through apertures in the blocks 10 and projecting therefrom and into screw threaded engagement with the blades. The unitary bridge construction and this mode of attaching the bridge section to the blades permit of readily replacing the bridge should the insulating member be damaged or broken in service or handling.

It will be evident that the use of the spaced screws 18 and 19 attaching the bridge section to the blades secures the blades rigidly in alinement and elfectively counteracts any tendency of the blades to pivot with respect to the bridge, that is, such tendency to pivot as might occur when the fuse is being inserted or withdrawn from a set of knife blade sockets.

If it is desired to increase the capacity of a fuse beyond the rating of a single fusible link 9, a plurality of such links may be used. For such an application the form of our invention illustrated in Fig. 4: is preferred, this form providing additional *ashers 21 between the links to properly space them.

As herein illustrated, the terminal blade unit is held centrally in the casing and against longitudinal movement by means comprising" the shoulders 15, the webs 5, the washers 13 and the screw-threaded end caps 14 which engage correspondingly screw-threaded portions of the heads2. These washers have slots therethrough as shown in Fig. 7 adapted to admit the terminal portion of the knife blade so that the washers may be slid on the blades and u a ainst the webs 5 and lates 12 and 12 As shown in Figs. 1 and 2 for the left hand end of the fuse, when the end caps 14 are screwed tightly on the heads 2, the shoulders 15 of the blades abut tiie webs 5, and the washers 13 contact the plates 12 and 12 and the heads, to hold the blades central in the casing and against longitudinal and transverse movement. The plates 12 and are adapted to fit snugly in the apertures 6 of the heads to prevent the blades from rotating therein. i

To replace a fuse link in a fuse of the preferred construction such as shown in the drawings, the end caps 14 are first unscrewed from the heads 2 and the left end cap 14 and washer 13 removed from the blade 8. The right end cap and washer are retained on the blade 8 by means of the upset portions 22 which project eclgewise of the blade. The blade 8 may then be moved transversely of the casing until the shoulders 15 on the blade register with the notches 7 after which the entire terminal blade unit may be withdrawn to the right, the said knifeblade 8 passing through the notches 7 in both heads and the plate 12 through the apertures 6. The terminal blade unit now being entirely removed from the casing, the'screws 19 may be loosened readily and the ends of the blown fuse link removed, the link 9 preferably having transverse open-ended slots 23 therein (as shown in Fig. 1) through which the screws 19 are adapted to pass. After inserting a new link, the screws 19 may be ti htened and the fuse reassembled by inserting the terminal blade unit into the casing, the blade 8 entering between the notches 7 of the heads. When the plate 12 enters the aperture 6 the blade 8 is central of the casing and the shoulders 15 of the blade abut the webs 5 to prevent further longitudinal movement inwardly. Then the wider terminal portion of the blade 8 has passed through the notches 7 in the left hand head, thus permitting a transverse movement of that blade to position it centrally of the head as shown in Fig. 5, with the shoulders 15 abutting the outward sides of the webs 5. The washers 13 may then be slid on the blades against the plates 12 and 12 and the caps 14 screwed tightly on the heads.

For properly venting the casing any suitable means may be provided to supplement the passages formed between the parts herein shown due to their relative positions or loosely fitting interengagement.

From the foregoing, it will be apparent that we have provided an improved cartridge fuse of simplified construction embodying a unitary terminal blade structure which is bodily removable from the casing and in which the terminal blades are secured in rigid alinement.

The means provided to secure fusible links to the terminal blades are of rugged and durable construction and thereby well adapted to resist wear, and require but a simple manipulation in the renewing of the links. This construction eliminates the necessity for loose nuts engaging bolts to clamp the fusible elements detachably to the blades and provides a complete closure for the threaded portion of the fastening devices to thereby prevent condensation of the vapors caused by fusion of the links. The fuse is particularly adapted to save time in the renewal of a blown link, and also permits of ready replacement of the insulating bridge section.

We claim as our invention:

1. A renewable cartridge fuse having, in combination, a casing, a terminal blade, an apertured washer slidable on said blade, and an end cap adapted to be detachably engaged with one end of said casing, said'blade having a projecting portion adapted to .retain said washer and end cap on said blade.

2. A renewable cartridge fuse having, in combination, a casing, a terminal blade, and means to secure said terminal blade to said casing, said means comprising an apertured washer slidable on said blade and an end cap slidab le and rotatable on said blade and adapted to be detachably engaged with one end of said casing, the opposite edges of said blade having upset portions adapted to retain said washer and said end cap on said blade.

3. A renewable cartridge fuse having, in combination, a tubular casing, a terminal blade, and means carried permanently on said blade adapted to secure the blade detachably to the casing and centrally thereof, said means including an end cap slidable longitudinally on and capable of rotary movement relative to the blade.

4. A removable terminal blade unit for a renewable cartridge fuse, comprising a pair of terminal blades, an insulating bridge seclion securing said blades in spaced relation, a fusible element detachably mounted between said blades and an end cap secured permanently and rotatably onone of said blades and adapted to secure said blade to and interlock it with a fuse casing by a rotary movement.

A terminal blade unit for cartridge fuses comprising, in combination, two blades, a' fusible element joining said blades, an insulatin g member, metallic block secured to each end of aid insulating member, means to secure said metallic blocks and insulating member to said terminal blades, and fastening devices extending through apertures in said fusible element and terminal blades and into screwthreaded engagement with said metallic blocks.

6. A terninal blade unit for cartridge fuses comprising, in combination, two blades, a metallic plate fastened transversely on each blade, a fusible element joining said blades, an insulating bridge section adapted to secure said blades in spaced relation, said bridge section comprising an insulating member and metallic blocks secured to the ends of said insulating member, means to secure said bridge section to said blades with the ends of said blocks in abutment with said plates, and fastening devices extending through apertures in said fusible element and blades and into detachable engagement with said metallic blocks.

7. A terminal blade unit for cartridge fuses comprising, in combination, two blades in spaced relation, a metallic plate fastened transversely on each of said blades, a fusible element joining said blades, and a bridge sec tion disposed alongside of said blades and in abutment with said plates, said bridge section including an insulating member spaced from said blades, and means detachably engaging said bridge section adapted to secure said fusible element and said bridge sect-ion to said blades.

8. A terminal blade unit for cartridge fuses comprising, in combination, two blades, a fusible element joining said blades, and an insulating bridge section securing said blades in spaced relation, said bridge section comprising an insulating member, metallic blocks secured to each end of said insulating member, said metallic blocks lying adjacent said blades to space the said insulating member therefrom. means projecting from said blocks and into engagement with said blades, and fastening devices extending through apertures in said fusible element and terminal blades and into screw-threaded engagement with said metallic blocks.

9. A terminal blade unit for renewable cartridge fuses. comprising, in combination,

n: lu

two-blades having apertures therethrough, an

insulating bridge section securing said blades in spaced relation, said bridge section comprising an insulating member and metallic blocks secured to the opposite ends thereof and positioned between said insulating memher and said blades, said blocks having screw threaded sockets therein closed at one end and alined with said apertures, and headed screw devices passing through said apertures and engaging in said sockets.

'10; A terminal blade unit for renewable cartridge fuses comprising, in combination, two blades in spaced relation, a fusible element connecting said blades, an insulating bar, and a pair of bolt and nut devices adapted to secure said fusible element detachably to said blades, one member of each of said devices being fixed to the opposite ends of said bar, said nut devices having their bolt receiving apertures closed at one end.

11. An insulating bridge section for securing in spaced relation the terminal blades of a renewable cartridge fuse in which the blades are joined by a fusible element, comprising, in combination, an insulating member, metallic blocks secured to the opposite ends thereof, a device pro]ecting from each of said blocks adapted to enter an aperture in a fuse blade, and screw-threaded apertures in said blocks spaced from said projecting devices and positioned to receive the fastening screws for the said fusible element.

12. An insulating bridge section for renewable cartridge fuses comprising,in combination, an insulating bar, and metallic blocks secured to the opposite ends of said bar, and having screw-threaded sockets therein closed at one end.

13. A renewable cartridge fuse having, in combination, an insulating tube, metallic heads secured to the ends thereof and having non-circular apertures, and a terminal blade unit, said unit comprising a pair of knife blade terminals connected by a fusible element and each having a shoulder on one edge thereof, a metallic plate fastened transversely on each blade, one of said plates being adapted to fit snugly in and close the aperture of one head with the blade central thereof and the blade shoulder abutting that head, the other plate fitting in and partially closing the aperture in the other head with the shoulder of its blade abutting the latter head when the blade is central of the casing, the latter plate being narrower at one side of the blade than the other, whereby said second blade is adapted to be moved transversely of the head to a position from which the'blade may be withdrawn through the casing.

14, A renewable cartrid e fuse having, in

combination, an insulating tube, metallic heads secured to the ends thereof, said heads having substantially rectangular apertures therein, and a terminal blade unit, said unit including a pair of knife blade'terminals having shoulders on the opposite edges-thereof adapted to abut against said heads and prevent inward movement of said blades, two substantially rectangular metallic plates fixed transversely on said blades and adapted to fit in said rectangular apertures, one of the plates fitting snugly in one aperture, the other plate being adapted for transverse movement in the other aperture, and means for securing said blades in place in said tube.

15. A renewable cartridge fuse comprising, in combination, a tubular casing having a non-circular end aperture therein, a terminal blade extending axially into the casing through said aperture and having a part to abut said casing to limit inward movement of said blade when centrally positioned, a non-circular plate fixed transversely on said terminal blade and adapted to fit in said aperture, said plate being narrower on one side of the blade than on the other, thereby permitting movement of said plate and blade in said aperture transversely of the axis of the casing, said casing permitting the blade to move further into the casing when so transversely displaced, and means to secure said blade in its central axial position.

16. A renewable cartridge fuse comprising, in combination, a tubular casing, a terminal blade projecting partially from one end of said casing, means to prevent inward movement of the blade when in a normal position central of the casing and to permit such movement when the blade is in a position eccentric in the casing, means carried by said blade adapted to abut said casing when in said normal position to prevent rotation of the blade in the casing and means to secure the blade to the casing in said normal position.

17. A renewable cartridge fuse comprising, in combination, a tubular casing having a non-circular aperture therein, a terminal blade carrying means to abut said casing when the blade is central thereof to prevent movement of the blade into the casing, a plate fixed transversely on said terminal blade adapted to engage in said aperture, said plate being narrower on one side of the blade than on the other to permit movement of the blade transversely of the casing to a position from which the blade may be moved into the casing.

18'. A renewable cartridge fuse comprising, in combination, a tubular casing having transverse webs defining an end aperture having substantially parallel sides, a terminal blade extending axially into said casing and having shoulders on the opposite edges thereof adapted to abut said webs, said webs having opposed notches therein in a plane eccentric of the axis of the casing, said blade being adapted to be moved transversely in the casing to a position wherein the said shoulders register with the said notches, and means tosecure the blade axially in the casing.

19. A renewable cartridge fuse comprising, in combination, a tubular casing having non-circular end apertures therein, a terminal blade unit comprising a pair of knife blade terminals joined by a fusible element and secured in longitudinally spaced relation,

said terminal blade unitbeing insertable through said casing with the advance blade eccentrically thereof, said advance blade being then movable transversely to an axial position to cause parts on said blades and casing to interlock to prevent longitudinal movement of the terminal blade unit, and means to s cure said blades to said casing in said axial position.

' 20. A renewable cartridge fuse comprising, in combination, a casing having duplicate non-circular end apertures therein, a pair of terminal blades extending into said casing and carrying non-duplicate transversely fixed plates adapted to engage said apertures to prevent rotary movement of the blades in the casing, said blades also carrying means to engage the ends of said casing to prevent longitudinal movement of the blades in the casing when axial thereof, and means to secure said blades axially of the casing.

21. A renewable cartridge fuse having, in combination an insulating tube, metallic heads secured to the ends thereof, said heads having webs at their outer ends defining noncircular apertures therein, a terminal blade unit including a pair of knife blade terminals rigidly secured together by an insulating bridge in longitudinally spaced relation and two metallic plates fixed transversely on said blades and adapted to fit in said apertures and prevent rotation of said unit, and detachable means engaging said heads for securing said unit in place in the tube.

22. A renewable cartridge fuse compris' ing, in combination, a tubular casing having non-circular end apertures, a terminal blade unit insertible as a whole into said casing through an end thereof, said unit including a pair of knife blade terminals rigidly secured together in longitudinally spaced relation by means of an insulating bridge, two non-circular metallic plates fixed transversely on said blades and adapted to lit in said non-circular apertures to prevent rotary motion of said unit, a pair of apertured washers slidable on said terminal blades externally of said casing, and a pair of end caps adapted to engage the ends of said casing to secure said washers and terminal blades against outward movement relative to the casing, said insulating bridge preventing inward movement of said terminal blades 28. A renewable cartridge fuse comprising, in combination, a tubular casing, metalsecure the blade he heads on said casing having end walls with non-circular apertures therein, eccentric portions of which are shaped to permit the passage of a knife blade therethrough, a. terminal blade unit comprising a pair of knife blade terminals in longitudinally spaced relation joined by a fusible element, said terminal blade unit being insertable through said casing with the advance blade passing through said eccentric portions of the head apertures, said advance blade being then movable transversely to an axial position to cause parts on said blades and heads to interlock to prevent longitudinal movement of the terminal blade unit, and means to secure said blades to said heads in said axial position.

24. A renewable cartridge fuse having in combination a tubular casing, a unitary terminal blade projecting partially from one end of said casing, means carried on the inner end of said blade adapted to secure one end of a fusible element thereto and means carried permanently on said blade adapted to detachably to the casing, said means including an end cap slidable longitudinally on and capable of rotary movement relative to the blade.

25. A removable terminal blade unit for a renewable cartridge fuse having a tubular casing, comprising a pair of terminal blades arranged to project partially from the ends of said casing when the unit is inserted therein, an insulating bridge section securing said blades together in spaced relation, means carried on the inner ends of said blades adapted to secure the ends of a fusible element thereto, means carried permanently on one of said blades adapted to secure that blade detachably to the fuse casing, said means including an end cap slidable longitudinally on and capable of rotary movement relative to the blade.

26. An insulating bridge section for re newable cartridge fuses comprising, in combination, an insulating bar, and metallic blocks secured to the opposite ends of said bar, said metallic blocks having screwt-hreaded apertures therein closed at one end by said bar.

27. A fuse comprising, in combination, a terminal blade having shoulders on opposite edges and an abutment adjacent said shoulders, a metallic head having an end wall closing a portion of the opening through the head, said end wall providing an opening having a narrow portion central of the head adapted to receive said abutment and a wider portion eccentric of the head through which said blade may be passed, and having portions at opposite ends of said narrow portion of the opening against which said shoulders abut to prevent movement of said blade inwardly in the head, and means cooperating with said head and said abutment on the blade to hold the blade in fixed position in the head.

28. A fuse comprising, in combination, a

v metallic head having an end wall closing a portion of the opening through the head, a disk closing the remainder of such opening, a terminal blade extending through said disk and into said head, said blade having shoulders at its edges arranged to abut against the outer face of said end wall to prevent inward movement of said blade, the blade also having an abutment arranged to engage the inner face of said disk to prevent outward movement of said blade, and means for securing said disk to said head, said securing means and disk being removable from said head and blade and said blade being then movable transversely and not rotatably rela tive to the'axis of the head to carry its shoulf ders out of abutting relation to said end wall, the blade then being movable longitudinally into the head through the end opening therein.

29. In a cartridge fuse, the combination of an insulating tube, av metallic head secured to one end thereof, said head having an end wall defining an opening having a narrow portion central of the head and a wider portion eccentric of the head, a terminal blade having a shoulder on one edge thereof, said shoulder, abuttingsaid end wall when the blade is central of the head to prevent inward movement of the blade in the head, said blade being adapted to be moved transversely into said wider eccentric portion of the aperture from which position it may be moved through the head.

30. A cartridge fuse comprising, in combination, an insulatingtube, a metallic head secured to one end thereof, said head having a transverse end wall defining an irregular opening, a terminal blade insertable through said opening eccentrically of said head and being then movable transversely to a central position wherein parts on said blade engage said end wall to prevent withdrawal of the blade.

In testimony whereof we have hereunto afiixed our signatures. 

